Switching mechanism



Oct. 13, 1942. A. L. JuDsoN 2,298,795

swITcHING MECHANISM Filed May 7, 1937 3 Sheets-Sheet l if-719.1 2 65)9219.4 ,77119.5

Oct. 13, 1942. A L. JUDSON SWITCHING MECHANISM Filed May 7, 1937 I5Sheets-Sheet 2 Il; H5 ne nol Oct. 13, 1942. A, L. JUDSON swITcHINGMECHANISM Filed May 7, 1937 3 Sheets-Shut 3 jlz'g. j]

latentes oci. 13, 1942 SWITCHIN G MECHANISM Albert L. Judson,Minneapolis, Minn., assigner to Minneapolis-Honeywell Regulator Company,Minneapolis, Minn., a corporation of Delaware Application May 7, 1937,Serial No. 141,299

29 Claims.

This invention relates to switching mechanism, more particularly to thattype of switching mechanism wherein a circuit making and breakingmechanism or analogous device is utilized to control apparatus in turncontrolling a condition in response to variations in the value of thecondition such as illustratively, temperature or pressure.

In devices of this character it is customary that the condition value atwhich the circuit controlled mechanism opens differ from the value atwhich the same closes and vice versa. A primary object of this inventionis to provide an improved means whereby the operating differential ofthe instrument may be readily varied in both directions, eachdifferential adjusting means being adapted to operate independently ofthe other.

An additional object of the invention is the provision of improveddifferential adjustment in combination with a leverage arrangementwhereby a lost motion connection may be provided between the operatingmechanism and the contact structure, and whereby the extent of such lostmotion connection may be readily varied in such manner that theoperating differential of the instrument may be increased or decreasedand the operating range varied upwardly or downwardly simultaneously.

An additional object is to provide in combination with the mechanism tobe hereinafter described as mentioned in the foregoing, means to imparta relatively rapid action to the switching mechanism, such action beingknown in the art as a snap action.

An additional and more specific object is the provision of visualindicating means in association with the differential adjustment abovementioned whereby the setting of the instrument may be readilydetermined at a glance.

A still further specific object is the provision of improveddifferential adjusting means of a novel type.

A further specific object is the provision of yieldable means inassociation with the differential adjusting means in combination withthe features set forth above whereby undue strain is precluded fromaffecting the contact structure or circuit controlling mechanism shouldsuch strain be imparted to other portions of the operating mechanism byundue condition value variation.

Further objects reside in the provision of a mechanism embodying theother objects of this invention as set forth in the foregoing whichlpart be pointed out hereinafter.

The invention accordingly consists in the combinations of elements,arrangements of parts and features of construction all as will be morefully pointed out hereinafter and disclosed in the accompanyingdrawings.

In the drawings wherein are shown several of the various possibleembodiments of this invention:

Figure 1 is a side fragmentary view partly in section of one form ofdevice incorporating features of the instant invention,

Figure 2 is a view similar to Figure 1, certain parts thereof beingomitted showing the mechanism in a different position of adjustment,

Figure 3 is a perspective view as taken from the upper left hand cornerof Figure 1,

Figure 4 is a sectional view taken along the line 4 4 of Figure 1 asviewed from the left,

Figure 5 is a fragmentary side view of certain portions of the mechanismshown in Figures 1 and 2 as viewed from the right,

Figure 6 is a side elevational view of a different embodiment of theinvention, certain parts thereof being shown in section,

Figure 7 is a sectional view taken along the line 'l-l of Figure 6 asviewed from the top,

Figure 8 is a perspective view showing one of the component parts of thedevice of Figure 6,

Figure 9 is a fragmentary sectional view taken along the line 9-9 ofFigure 6 as viewed from the top,

Figure 10 is a fragmentary view of mechanism similar to that shown inFigure 6 showing various modified constructional details,

Figure 11 is a side elevational view partly in section of a stillfurther modified form of structure embodying this invention,

Figure l2 is a side sectional view taken along the line I2-l2 of Figure11, and

Figure 13 is a perspective view ci certain of the component parts of thestructure shown in Figures ll and 12.

Similar reference characters designate similar parts throughout theseveral views of the drawings.

Having reference now to the drawings, and more particularly to Figures 1to 5 inclusive, there is disclosed at 20 a fragment of a casingcontaining the operating mechanism of this embodiment of the invention.Secured to the base of casing 20 as by suitable screws 2l is a housing22 to the base of which is secured a nipple 23 having a suitableaperture therein into which extends a threaded end of a pressure tube 24which extends from any suitable source of pressure which is adapted tobe positioned in any desired location, the temperature, pressure orother condition of which it is desired to control. Housing 22 contains abellows 25 to the lower end of which is secured an operating rod 26which extends upwardly out of housing 22 and terminates in a point 21. Asuitable spring 28 serves to bias bellows 25 downwardly against thepressure exerted thereon by the volatilized fluid in housing 22. The end21 of operating rod 26 engages a recess 30 in a boss 3| carried by alever 32. Lever 32 is pivotally mounted as on a pivot 33 the ends ofwhich are carried by a U- shaped bracket 34 supported on the base ofcasing 20. A spring 40 is secured in any desired manner in positionbetween one end of lever 32 and the base of casing and serves to biaslever 32 about its pivot 33 against the pressure exerted by operatingrod 26, spring however is not sufficiently strong to effect theoperation of operating rod 26 and serves only to maintain recess 30 inclose juxtaposition with point 21 upon a drop in pressure in housing 22.The end of lever 32 opposite spring 40 carries a pair of upwardlyprojecting lugs 4| through suitable apertures in which is passed a pivotpin 42. pin 42 is a second lever 43 provided with an extending portion44, the purpose of which will be more fully described hereinafter, and asecond extending portion 45. Portion 45 is provided at its end with aslot 46 adapted to engage a pin 41 carried by a U-shaped member 48 whichlatter is pivotally mounted as by pivot pins 49 on bracket 34. Securedto bracket member 48 in any desired manner is a mercury switch clip 50in which is positioned a mercury switch 5|. As better shown in Figure 3that side of bracket 48 opposite mercury switch clip 50 carries a pin52. That leg of bracket 34 disposed adjacent pin 52 is provided with apair of upstanding lugs 53 positioned on either side of pin 52 andserving as a stop therefor for a purpose to be hereinafter described.

Referring back to portion 44 of lever 43 it will be seen that portion 44extends between two cam shaped members 60, having bevelled edges a inorder to provide a knife edge contact surface. Cam shaped members 60 arecarried by a pair of rods 6| disposed on opposite sides of portion 44and provided with flattened portions 62 which serve to preclude rotationof cams 60 thereupon. Nuts 63 engaging the ends of rods 6| serve to holdthe component parts assembled thereon in related assembly.

Spacers 64 are provided adjacent cams 60 and positioned adjacent spacers04 are a second pair of cams 65. Spring collars 10 are interposedbetween cams 65 and the side wall of casing 20. Extending exteriorly ofcasing 20 and mounted upon the exterior extremity of screws 0| are knobs1| provided with pointers 12 and knurled heads 13. As better shown inFigure 5 the wall of casing 20 adjacent knob 13 is provided with indiciawith which pointers 12 cooperate.

From the foregoing the operation of the mechanism should now be obvious.As the pressure in housing 22 is increased by the increase intemperature or other condition in the space adjacent the volatile fluidfilled bulb operating rod 26 is forced upwardly and through theengagement of point 21 with recess 30 moves lever 32 up- Secured topivot Cil wardly correspondingly. This movement of lever 32 will have noeffect on mercury switch 5| until such time as extension 44 of lever 43engages the beveled surface of the upper of cams 60. At this timecontinued upward pressure on lever 32 will cause pivotal movement oflever 43 about its pivot 42 with respect to lever 32 and throughaperture 46 and pin 41 will cause bracket 48 to be rotated about itspivots 49 and hence tilt mercury switch 5| to open or closed circuitposition depending upon the position of the electrodes (not shown) ofthe mercury switch 5|. correspondingly as the pressure decreases inhousing 2|, spring 40 will force that end of lever 32 adjacent lever 43downwardly until extension 44 engages the adjacent surface of the lowerof cams 60 at which time further reduction in pressure in housing 22will permit extension 45 of lever 43 to move downwardly and through thepin and aperture connection previously described move bracket 48 to theopposite position. Projections 53 serve to limit the tilting movement ofthe bracket 48 and hence of mercury switch 5|, in order that the switchmay be limited to movement Within its desired normal angle oflnclination.

From a consideration of Figures 4 and 5 it will be seen that the cams 60may be rotated by means of knurled portions 13 of knobs 1| in order tovary the distance therebetween and that such variation of the distancetherebetween will cause a divergence in the operating differential ofthe mechanism. It will be seen additionally that by rotation of the camsa constant differential may be maintained and yet the high and lowpoints thereof be varied within the operating limits of the mechanism asdefined by the cams. For example, when a low dwell of the upper of cams60 is adjacent extension 44 and a high dwell of the lower of cam 60adjacent thereto the differential of operation will be at a minimum andwithin the higher range of the device. When the converse is true thedifferential will be correspondingly narrow but within the lower rangeof the device. Similarly when a low dwell of each of cams 60 is adjacentextension 44 the differential will be exceedingly wide and range fromthe high operating limits to the low operating limits of the device.

As shown in Figures 1, 4 and 5 knobs 1| are so set that an intermediateportion of each of the cams are adjacent extension 44, thus thedifferential is as narrow as possible and the operating range is at themid point of the possible scale setting. By rotating the lower of knobs1| to the left as viewed in Figure 5 a low dwell of the lower of cams 60is brought adjacent extension 44 and by rotating the upper of knobs 1|to the right a low dwell of the upper of cam 60 is brought adjacentextension 44. Thus by such rotation it will be seen that the upper andlower operating limits of the device are diverged and by such divergencethe operating differential of the instrument increased. From the aboveit will readily be seen that the converse of this operation is alsotrue.

Referring now to the Figures 6 to 10 inclusive there is disclosed adifferent modification of the inventive concept but one wherein theprinciples of operation disclosed in the foregoing modification are alsoembodied.

A casing |00 has secured thereto a housing I0| as by the engagement of alock nut |02 with an upwardly extending threaded portion |03 whichpasses through a suitable aperture in the base of casing |00.

In the form shown in Figure .6 the base |04 of housing is provided witha downwardly extending nipple |05 having a threaded portion to which isadapted to be secured a pressure tube leading from any suitable sourceof pressure (not shown). A bellows |06 is contained within housing |0|and secured to the base |04 thereof. A spring |01 abuts a shoulder |08of base |04 and biases bellows |06 upwardly for a purpose to bedescribed hereinafter. A stop |09 is interposed between spring 01 andbellows |06 to prevent complete collapse of bellows |06. An operatingrod ||0 extends upwardly from the top of bellows |06 through a suitableaperture in threaded portion |03 into casing |00. The upper end ofoperating rod ||0 seats in a recess in a lever ||2. Lever ||2 is pivotedas by a pivot pin 3 to a second lever |4 which is in turn pivoted as bya pivot I5 to a bracket |6 secured to the side wall of casing |00. Lever|4 is provided with two extending portions and |2| positioned forabutment respectively with a pair of screws |22 and |23 provided withknurled and enlarged heads which extend through suitable threadedapertures exteriorly of casing |00. A screw |25 extends through anopening in the top wall of casing |00 and is rotatably secured theretoas by a collar |26. Screw |25 threadedly engages a boss |21 to which inturn is secured a spring |28. The lower end of spring |28 is secured toa plate |29 which carries a point |30 adapted to engage lever ||2 at apoint substantially opposite the point of engagement of operating rod||0 therewith.

As better shown in Figure 9 an extending member is secured to boss |21and passes into a slot |36 in the side wall of casing |00. Thus it willbe seen that rotation of screw |25 is not imparted to spring |28 sincerotation thereof is precluded by member |35 but that such rotationincreases or decreases the compression in spring |28 for a purpose to behereinafter described.

Lever ||2 is provided with an extending portion |40 which is providedwith a pair of slots |4| and |42. In one of the slots, slot |4| asshown, is positioned a pin held in place as by a lock nut |46. A bracket|41 extends upwardly from the base of casing |00 and is secured theretoas by screws |48. Pivotally mounted on bracket |41 as by a pivot |1| isa member generally indicated at comprised of, as best shown in Figure 8,an extending portion |5| having two slots |52 and |53 therein and aninsulating block |54 rigidly secured to extending member |5|. With theparts in related assembly pin |45 extends into one of slots |5| or |53dependent upon which of slots |4| or |42 the same is initiallypositioned in. The illustrative embodiment discloses pin |45 asextending into slot |52. Secured to insulating block |54 as by a screw|55 is an extending member |56 which carries a contact |51. Positionedadjacent contact |51 and carried by an insulating panel |61 is a secondcontact |58 and surrounding contact |58 is a horse- `,renee-magnet4.59secured to panel |61 as by a bar and screw |6|. A pair of terminals |62and |63 may be electrically associated in any desired manner withcontact |58 and contact |51 respectively, as for example a wire |65 mayextend from terminal |63 to screw |55. A coil spring |10 is positionedabout pivot |1| and serves normaly to bias contact |51 in a directionaway from engagement with contact |58.

From the foregoing the operation of the mechanismwill be readilyunderstood by those skilled in the art.

An increase in pressure in the space the pressure of which it is desiredto control will cause the expansion of bellows |06 and move operatingrod ||0 upwardly. Such movement will be transmitted to lever ||2 whichin turn will move upwardly carrying with it lever |-4 and consequentlyrotating about pivot ||5 until such time as arm |20 of lever ||4 abutsscrew |22 to preclude further movement of lever |4. At this time upon afurther increase in pressure lever I2 will rotate about pivot ||3 andthrough pin |45 cause member |50 to move contact |51 into engagementwith contact |56. Upon a drop in pressure in bellows |06 it will bereadily understood that the opposite action will take place whencontacts |56 and |51 separate. In this case no movement will be impartedto contact |51 until arm |2| abuts screw |23. It will thus be seen thatby varying the position of the ends of screws |22 and |23 the operatingdifferential of the instrument may be varied over a wide range since nomovement of contact |51 can take place in either direction until arm |20or arm |2| has engaged its associated screw abutment.

It should here be pointed out that spring |01 biasing bellows |06upwardly permits the instrument to be operated at sub-atmosphericpressures since upon the creation of a partial vacuum in bellows |06 theatmospheric pressure in housing |0| will compress the same to moveoperating rod |0 downwardly whereupon lever ||2 will be forceddownwardly by compression spring |28 to separate contacts |56 and |51.Should reverse action of the instrument be desired it will be readilyunderstood that by positioning pin |45 and its associated lock nut |46in slot |42 whereby pin |45 will engage slot |53, contacts |56 and |51may be opened upon an increase in pressure in bellows |06 and closedupon a decrease in such pressure. The pressure or other analogouscondition value at which the instrument operates may readily be variedby varying the compression in spring |28 as it will readily beunderstood that an increased cornpression in spring |28 will requirehigher pressure to open or close contacts |56 and |51 whereas a lowercompression will require a decreased ressure, the converse being truewhen the instrument is operated at subatmospheric pressures if desired.

It will be understood however, that the adjustment hereinbeforedescribed of screw |25 by which the compression of spring |28 is variedmay be omitted if desired without affecting operation of the instrumentinasmuch as substantially the same results may be achieved by suitableadjustments of screws |22 and |23. This particular structure is ofparticular utility in those cases where it is desired that theinstrument respond to temperature rather than pressure and wherein oneof the screws |22 or 23 is omitted for a reason to be hereinafterdescribed.

An instrument of analogous character but designed to respond tovariations in temperature rather than pressure is disclosed in Figure10. In this case screw |22 is supplanted by an abutment |15 and bellowsassembly contained within housingr |0| is varied to the extent that baseplate |04 is provided with a boss |16 to which is suitably secured acapillary tube |11 leading from a suitable volatile fluid iilled bulb(not shown). In such a case pivot I3 is supplanted by a pivot pin ||3'positioned relatively closer to pivot ||5 in order to provide a greatermechanical advantage over lever ||2. This is desirable for the reasonthat temperature controlled instruments are unable to exert the force ofcorresponding pressure controlled instruments and further because thedifferential adjustment utilized in connection with pressure controlledinstruments need not be as wide as that used in connection withinstruments of the pressure type. Therefore, it will be readilyunderstood that the instrument as shown in Figure may be suitablycalibrated by means of screw |25 and screw |23 in a manner similar tothat discussed in connection with the device operated. by pressure asshown in Figure 6.

With the above noted exceptions, the parts disclosed in Figure 10 areidentical to those disclosed in Figure 6, and accordingly, referencecharacters denoting identical parts in Figure 6 are utilized in Figure10.

A still further modified form of the inventive concept is disclosed inFigures 1l to 13 inclusive. Having reference now to these figures acasing 200 has secured thereto as by screws 20|, a housing 202 providedat its lower extremity with a boss 203 to which is attached a capillarytube 204 leading to a suitable source of pressure (not shown). Housing202 contains a bellows 205 having a base plate 206 to which is securedan operating rod 201 which extends upwardly into casing 200 andterminates in a point 208. A stop 209 is positioned within bellows 205and terminates in a flange 2|0 which supports one end of a compressionspring 2||, the other end of which abuts a collar 2|2 positioned about0perating rod 201. Spring 2|| serves normally to compress bellows 205whereby the structure shown in Figures 11 to 13 may be advantageouslyutilized to operate at subatmospheric pressures since operating rod 201will be forced upwardly by spring 2|| as long as the pressure in housing202 is equal to or above atmospheric pressure. It will of course beunderstood that the device may be so constructed as to operate onpressures greater than atmospheric merely by the omission of spring 2|Point 208 abuts a lever 2|5 which is pivoted as by a pivot 2|6 to asecond lever 2|1 which is in turn pivoted as by pivot pin 2|8 to abracket 2|9 secured to the side wall of casing 200. As better shown inFigure 12 lever 2|1 is comprised of a bracket like member having twoextending portions 225 and 226, the purpose of which will be hereinafterdescribed. A screw 229 is non-rotatably secured to the top wall ofcasing 200 and threadedly engages a boss 230 to which is secured aspring 23|. The other end cf spring 23| is secured to a second boss 232which has aixed thereto a point 233 positioned for abutment with lever2|5 at a point diametrically opposed to the point of abutment of point208. A pair of levers 240 and 24| are pivotally mounted on pivot pin2|8. Lever 240 is provided with an extending abutment portion 242 and sopositioned that it may engage extending portion 226 and its dependingflange 221 of lever 2|1. Lever 24| is provided with an abutment 245 asbetter shown in Figure 13 positioned to engage portion 225 of lever 2|1.Each of members 240 and 24| is provided with an extension 250 and 25|respectively, each of which has a threaded aperture passed therethroughto accommodate respectively screws 252 and 253. Screw 253 extendsoutwardly through a suitable aperture in the side wall of casing 200 andhas positioned thereabout and secured thereto a spring collar 254 whichserves to bias the same inwardly for a purpose to be describedhereinafter. Screw 252 extends similarly out through an aperture incasing side wall 200 and is provided with an outwardly disposed collar255 which serves to bias the same outwardly with respect to casing 200,also for a purpose to be more fully described hereinafter. Levers 240and 24| terminate respectively in pointers 260 and 26| disposed adjacenta scale plate 262 secured in any desired manner to the top wall ofcasing 200.

Referring back to lever 2| 5 as best shown in Figure 11 it will be seenthat the same is provided with a disaligned portion 210 and likewisewith a resilient member 21| secured thereto in any desired manner as bya rivet 212 to provide a slot at the extremity thereof. The slotcomprised of bent portion 210 and resilient member 21| is positioned toengage a pin 213 carried by an insulating block 214 which is pivoted asby a pin 215 in a bracket 216 carried by the base of casing 200.insulating block 214 has projecting upwardly therefrom a contactcarrying arm 218 which extends through a suitable aperture into ahousing 219 of insulating material. Housing 219 carries thereinoppositely disposed contacts 280, 28|, 282 and 283 positioned forengagement with contact buttons 284 and 285 carried by a member 286 inturn carried by a member 218. Magnets 290 and 29| having incut edges 292and 293 respectively aie held in position in housing 219 as by screws294 and 295 and bars 296 and 291. Suitable electrical connections extendfrom each of contacts 280, 28|, 282 and 283 to any desired source ofcondition control. These electrical connections may advantageously takethe form disclosed in the copending application of Carl G. Kronmillerand Albert L. Judson, Serial No. 141,300, led of even date herewith.

The operation of the device should be readily understood from theforegoing. Assuming the parts to be in the position shown in Figure 1l,it will be seen that an increase in pressure in housing 202 willoccasion an upward movement of operating rod 201 causing lever 2|5 topivot about pin 213 and similarly lever 2|1 about pivot 2| 8 until suchtime as portion 226 of lever 2|1 engages abutment 242 of member 240 atwhich time further movement of lever 2|1 is precluded. Lever 2| 5 willthen move about pivot 2|6 and through the pin 213 and the apertureformed by bent portion 210 and yieldable portion 21| be transmitted tocontact carrying member 218 and hence to contacts 285 and 286. Thedevice is shown in Figure 11 in a position indicating a low pressure inhousing 202 and upon an increase in pressure contacts 284 and 280 willengage as will contacts 285 and 282. As the contact carrying arm 218 ismoved past center position it will enter the magnetic eld of magnet 290and be pulled in a direction towards contacts 280 and 282 with arelatively snap action. Correspondingly upon a decrease in pressure theconverse action will take place t0 bridge a circuit between electricalcontacts 28| and 283, magnet 29| serving to complete a snap action tothe reverse motion of the device in a manner similar to that justdescribed. Upon such a reverse movement of the device it will beunderstood that lever 2|5 will move with lever 2|1 until such time asportion 225 of lever 2|1 engages-abutment 245 of member 24| whereuponlever 2|5 will move about its pivot 2|6 to impart reverse movement tocontact carrying member 218. It

should here be pointed out that magnets 290 and 29| may, due to theinclined or bevelled edges 292 and 293 be positioned in a relativelylimited space in housing 219 and at the same time exert a relativelygreat magnetic force on contact carrying member 286.

It will additionally be seen that rotation of boss 230, by increasingthe compression on spring 23|, will vary the condition value to whichthe device responds in a manner similar to that disclosed in connectionwith the modification of Figures 6 to 10. Correspondingly by rotatingscrew 253 the position of abutment 245 may be changed while rotation ofscrew 2512 will change the position of extending portion 242 to providea variable operating differential for the instrument. Pointers 260 and26| will moreover indicate the relative operating differential on scaleplate 262 in such manner that the adjustment of the instrument may bereadily determined by examination. From the foregoing it will be seenalso that the tendency of arm 24| is to pull screw 253 inwardly withrespect to casing 200 and that consequently it is necessary thatresilient collar 254 be positioned interior-ly of the casing to hold thehead of screw 253 together against the casing to preclude any lostmotion and overcome such tendency. Conversely, lever 240 tends to forcescrew 252 outwardly with respect to casing 200 and thus spring collar255 is positioned exteriorly of the casing.

In the foregoing there have been described three illustrativeembodiments of this inventive concept which, as will be seen, accomplishthe objects of this invention and many others including numerousadvantages of great practical importance.

As many additional embodiments may be made of this invention and as manymodifications may be made in the embodiments above described andillustrated in the drawings it is to be understood that all such matterhereinbefore described or shown in the accompanying drawings is to beinterpreted as illustrative and not in a limiting sense.

I claim as my invention:

1. In a device of the character described, in combination, a movablemember, a lever movable thereby, a second lever associated with said rstlever and movable thereby, contact means movable by said first lever,abutment means disposed adjacent an end of said second lever, thearrangement being such that said movable contact is not moved until saidfirst lever has moved said second lever into engagement with one of saidabutments and yieldable means associated with said second lever and saidcontact mechanism whereby excessive motion of said second lever is nottransmitted to said contact means.

2. In a device of the character described, in combination, a movablemember, a lever movable thereby. a second lever associated with saidfirst lever and movable thereby, contact means movable by said firstlever, abutment means disposed adjacent an end of said second lever, thearrangement being such that said movable contact is not moved until saidfirst lever has moved said second lever into engagement with one of saidabutments, yieldable means associated with said second lever and saidcontact mechanism whereby excessive motion of said second lever is nottransmitted to said contact means, and means for varying the position ofsaid abutments with respect to said end of said second lever.

3. In a. device of the character described, in

combination, a movable member, a lever movable thereby, a second leverassociated with said first lever and movable thereby, contact meansmovable by said first lever, abutment means disposed adjacent an end 0fsaid second lever, the arrangement being such that said movable contactis not moved until said first lever has moved said second lever intoengagement with one of said abutments, yieldable means associated withsaid second lever andv said contact mechanism whereby excessive motionof said second lever is not transmitted to said contact means, and meansfor independently varying the position of each of said abutments withrespect to said end of said second lever.

4. In a device of the character described, in combination, a movablemember, a lever movable thereby, a second lever associated with saidfirst lever and movable thereby, contact means movable by said firstlever, abutment means disposed adjacent an end of said second lever, thearrangement being such that said movable contact is not moved until saidfirst lever has moved said second lever into engagement with one of saidabutments, yieldable means associated with said second lever and saidcontact mechanism whereby excessive motion of said second lever is nottransmitted to said contact means, means for independently varying theposition of each of said abutments with respect to said end of saidsecond lever and visual means for indicating the relative position ofeach of said abutments.

5. In a device of the character described, in combination, a movablemember, a lever movable thereby, a second lever associated with saidfirst lever and movable thereby, contact means movable by said firstlever, abutment means disposed adjacent an end of said second lever, thearrangement being such that said movable Contact is not moved until saidfirst lever has moved said second lever into engagement with one of saidabutments, yieldable means associated with said second lever and saidcontact mechanism whereby excessive motion of said second lever is nottransmitted to said contact means and means to impart a relatively snapaction to the movement of said contact mechanism.

6. In a device of the character described, in combination, a movablemember, a lever movable thereby, a second lever associated with saidfirst lever and movable thereby, a fixed contact, a movable contactadapted to engage said fixed contact upon movement of said firstmentioned lever in one direction, a pair of oppositely disposedabutments positioned adjacent an end of said second lever, means forindependently varying the position of each of said abutments and meansassociated with said movable contact and said second lever whereby saidmovable contact may be made to disengage said first mentioned contactupon movement of said lever in said same direction.

7. In a device of the character described, in combination, a movablemember, a lever movable thereby, a second lever associated with saidfirst lever and movable thereby, a fixed contact, a movable contactadapted to engage said fixed contact upon movement of said iirstmentioned lever in one direction, a pair of oppositely disposedabutments positioned adjacent an end of said second lever, means forindependently varying the position of each of said abutments, meansassociated with said movable contact and said second lever whereby saidmovable contact may be made to disengage said first mentioned contactupon movement of said lever in said same direction and means forimparting a relatively rapid snap action to the movement of said movablecontact, said means comprising a magnet associated with one of saidcontacts.

8. In a device of the character described, in combination, a movablemember, a lever movable thereby, a second lever associated with said rstlever and movable thereby, mechanism controlled by said levers, twooppositely positioned abutment means adjacent an end of one of saidlevers, the arrangement being such that said mechanism is not operateduntil one of said levers has engaged said abutment means, means forindependently varying the position of each of said abutment means withrespect to said end of said lever and means for imparting a relativelyrapid snap action to the movement of said controlled mechanism.

9. In a device of the character described, in combination, a conditionresponsive member, a lever adjacent said member and movable thereby, asecond lever pivoted on said rst lever, said second lever being providedwith a pair of extending portions, a pair of abutment members disposedeach adjacent one of said extending portions, contact means associatedwith an end of said first mentioned lever, the arrangement being suchthat said lever is incapable of moving said contact means until it hasmoved said second lever to such position that one of said extendingportions is engaged by its associated abutment member, and means forvarying the relative position of each of said abutment members withrespect to its associated extending portion independently of the other.

l0. In a device of the character described, in combination, a conditionresponsive member, a lever adjacent said member and movable thereby, asecond lever pivoted on said first lever, said second lever beingprovided with a pair of extending portions, a pair of abutment membersdisposed each adjacent one of said extending portions, contact meansassociated with an end of said first mentioned lever, the arrangementbeing such that said first lever is incapable of moving said contactmeans until it has moved said second lever to such position that one ofsaid extending portions is engaged by its associated abutment, means forvarying the relative position of each of said abutment members withrespect to its associated extending portion independently of the otherand visual means indicating the relative position of each of the saidabutment members With respect to its associated extending member.

11. In a device of the character described, in combination, a movablemember, a lever movable thereby, a second lever movable by said rstlever, abutment means adjacent an end of said second lever, mechanismoperable by said second lever adjacent the opposite end thereof, saidsecond lever being inoperative to operate said mechanism until saidfirst lever has moved said rst mentioned end into operative associationwith said abutment, whereby said second lever is moved only by theconjoint action of said rst lever and said abutment.

12. In a device of the character described comprising in combination, alever, a control member, one end of said lever being free to move, meansto limit positively the amount of such movement in each direction, theother end of said lever being operatively associated with said controlmember, and condition responsive means for first moving the free end ofsaid lever to one of its limits and then moving said other end toactuate said control member.

13. In a device of the character described comprising in combination, alever, a control member, one end of said lever being free to move, meansto limit positively the amount of such movement, the other end of saidlever being operatively associated with said control member, conditionresponsive means for first moving the free end of said lever to one ofits limits and then moving said other end to actuate said controlmember, and means for individually adjusting each of said limits.

14. In a device of the character described comprising in combination, alever, a pivotally mounted arm, a switch mounted for actuation thereby,one end of said lever being free to move, means to limit positively theamount of such movement in each direction, the other end of said leverbeing pivotally connected to said arm, and condition responsive meansengaging said lever between said ends to cause it to pivot about itsconnection to said arm until its free end reaches one of its limitsafter which the other end of said lever rotates said arm to cause switchactuation.

15. In a device of the character described comprising in combination, alever, a pivotally mounted arm, a switch mounted for actuation thereby,one end of said lever being free to move, means to limit positively theamount of such movement, the other end of said lever being pivotallyconnected to said arm, condition responsive means engaging said leverbetween said ends to cause it to pivot about its connection to said armuntil its free end reaches one of its limits after which the other endof said lever rotates said arm to cause switch actuation, and means forvarying the distance between said limits.

16. In a device of the character described comprising in combination, alever, a pivotally mounted arm, a switch mounted for actuation thereby,one end of said lever being free to move, means to limit positively theamount of such movement, the other end of said lever being pivotallyconnected to said arm, condition responsive means engaging said leverbetween said ends to cause it to pivot about its connection to said armuntil its free end reaches one of its limits after which the other endof said lever rotates said arm to cause switch actuation, means forindividually adjusting each of said limits, and means for indicatingeach of said adjustments.

17. In a device of the character described comprising in combination, alever, a pivotally mounted arm, a switch mounted for actuation thereby,one end of said lever being free to move, means to limit the amount ofsuch movement, the other end of said lever being pivotally connected tosaid arm, condition responsive means engaging said lever between saidends to cause it to pivot about its connection to said arm until itsfree end reaches one of its limits after which the other end of saidlever rotates said arm to cause switch actuation, means for varying thedistance between said limits, resilient means for opposing movement ofsaid lever by said condition responsive means, and adjustable means forvarying the force exerted by said resilient means.

18. In a device of the character described comprising in combination, alever, a condition responsive device for moving said lever, a pivotallymounted contact arm, a spring tending to rotate said arm in onedirection, a magnet tending to rotate said arm in the oppositedirection, one end of said lever `being connected to said contact armfor rotating it about its pivot, the other end of said lever being freeto swing, and adjustable means for limiting the amount of said swing.

19. In a device of the character described cornprising in combination, alevel', a condition responsive device for moving said lever, a pivotallymounted contact arm, magnets on either side of said arm, one trying torotate it one direction and the other trying to rotate it in the other,one end of said lever' being connected to said contact arm for rotatingit about its pivot, the other end of said lever being free to swing,adjustable means for limiting the amount of said swing, and a resilientmember on said lever permitting overrun of said condition responsivedevice.

20. In a device of the character described comprising in combination, alever, a condition responsive device for moving said lever, a switcharm, a switch adapted to be actuated by said arm, one end of said leverbeing operatively connected to said switch arm whereby the latter isoperated by the former, the other end of said lever being free to swing,and means for limiting said swing in each direction, said meanscomprising a pair of individually adjustable cams.

21. In a device of the character described comprising in combination, alever', a condition responsive device for moving said lever, a pivotedswitch arm having two extensions, one on each side of said pivot, meansfor connecting one end of said lever to either one of said extensionswhereby movement of said lever in one direction may be made to rotatesaid switch arm in either direction, the other end of said lever beingfree to swing, and adjustable means lor limiting the amount of saidswing in each direction.

22. In a device of the character described, in combination, a movablemember, a lever movable by said member, a second lever substantiallyparallel to said first mentioned lever and adjacent thereto, said rstlever so positioned as to abut an intermediate portion of said secondlever whereby movement of said movable member is transmitted to saidsecond lever only through said rst lever, means to vary the position ofan end of said second lever with respect to said first lever, andmechanism operated by said second lever.

23. In a device of the kind described, a base, a lever having a free endand a fulcrum portion, both being displaceable by translation, fulcrummeans on said base comprising two fulcrum elements for said lever, powermeans connected to the lever to move it in two directions to bring itsfulcrum portion against said fulcrums, the ful crum portion abutting oneof said fulcrum elements in one direction of its travel, and the otherfulcrum element in the other direction, and said power means thereaftermoving the lever against the respective fulcrum to shift the free end,and one of said fulcrum elements being adjustable relative to the otherso that the free end of the lever will be displaced at one point ofmovement of said power means in one direction, and at another point inthe other direction, and means actuated by the free end of the lever.

24. In a device of the character described, power means, a lever, spacedabutment means adapted to be engaged by one portion of said lever forlimiting its motion in each direction, a control member associated witha second portion of said lever for actuation thereby, means operativelyconnecting said power means with a third portion of said lever, andmeans yieldably resisting movement of the second portion of said leverwhereby said rst portion is always moved firstl by said power means intoengagement with one of said abutment means after which said secondportion is moved to actuate said control member.

25. In a device of the kind described, power means, including a memberexpansible and contractible, a lever, means transmitting movements ofthe member to the lever including an adjustent mechanism for presettingthe position of the lever relative to the expansible member, meansnormally releasably urging one end of the lever into either of twoopposite positions, and a pair of opposed, relatively adjustablel'ulcrums for the opposite end of the lever, said power means beingadapted to displace the fulcrum end of the lever to a fulcrum, andthereafter to pivot the same about the fulcrum to displace its other endagainst the moving of the yieldable means.

26. In a device of the character described, power means, a lever, meansconnecting said power means to one portion of said lever wherebyrotative movements of said lever may be controlled by said power means,a pair of abutment means limiting the movement of another portion ofsaid lever in both directions, a control device actuated by a thirdportion of said lever, and magnetic means cooperating with said controldevice to produce a snap action.

27. In a device of the character described comprising in combination, afirst lever, a condition responsive member for moving said lever, afreely movable second lever, said first lever being connected at one endto said second lever for moving the same, stop means for limiting themovement of said second lever in each direction, a control deviceactuated between first and second positions by the other end of saidfirst lever, and magnetic means cooperating with said control device forresisting its movement from each of its said positions whereby uponmovement of said condition responsive device said first lever firstmoves said second lever until its movement is limited by said stopmeans, and thereafter upon continued movement of said conditionresponsive member said first lever' actuates said control device with asnap action.

28. In a device of the character described comprising in combination, afirst lever, a condition responsive member for moving said lever, afreely movable second lever, said first lever being connected at one endto said second lever for moving the same, stop means for limiting themovement of said second lever in each direction, a control deviceactuated between first and second positions by the other end of said rstlever, magnetic means cooperating with said control device for resistingits movement from each of its said positions whereby upon movement ofsaid condition responsive device said first lever first moves saidsecond lever until its movement is limited by said stop means, andthereafter upon continued movement of said condition responsive membersaid rst lever actuates said control device with a snap action, meansfor varying the condition values at which said second lever reaches eachlimit of its movement, and means for indicating said condition values.

29. In a device of the character described comprising in combination, afirst lever, a condition responsive member for moving said lever, afreely movable second lever, said first lever being connected at one endto said second lever for moving the same, stop means for limiting themovement of said second lever in each direction, a control deviceactuated between first and second positions by the other end of said rstlever, magnetic means cooperating with said control device for resistingits movement from each of its said positions whereby upon movement ofsaid condition responsive device said first lever rst moves said secondlever until its movement is limited by said stop means, and thereafterupon continued movement of said condition responsive member said firstlever actuates said control device with a snap action, and means forvarying the condition values at which said second lever reaches eachlimit of its movement, said last named means including means for varyingat least one of said values independently of the other.

ALBERT L. JUDSON.

